Cooling Fan: Overheat Protection Device

If a cooling fan in operating status locks due to overload, the ambient temperature rises rapidly, or the input current increases for some reason, the cooling fan's temperature rises abruptly. If the cooling fan is left in this state, the insulating performance within the cooling fan may deteriorate, reducing its lifetime and, in extreme cases, burning out the winding and causing a fire. To protect the cooling fan from such abnormal thermal phenomena, the following overheat protective devices are provided.

Thermal Protector (Automatic Return Type)

The structure of the thermal protector is shown in the figure below.
For information on the overheat protection of each product, refer to the product page.

The thermal protector employs a bimetal system.

Operating Temperature of Thermal Protector

Open:

120±5 °C
(Operating temperatures may vary depending on the model.)

Close:

76±20 °C
(Operating temperatures may vary depending on the model.)

(The cooling fan winding temperature, where the thermal protector is activated, is slightly higher than the operating temperature listed above.)

Impedance Protection

Impedance protected fans are designed with higher impedance in the cooling fan windings so that even if the cooling fan locks, the increase in current (input) will be minimized and temperature will not rise above a certain level.

Burnout Prevention Circuit

DC fans are equipped with a burnout prevention circuit that cuts the power to the windings or limits the current when the rotor is locked.

For information on the overheat protection of each product, refer to the product page.